Wow...lemme see if I can take a stroll down the memory lane with this one!
2007 -

My first phone was a Nokia 1600b.This was gifted by my dad when I went away for medical entrance coaching for a month. Loved the way it felt in the hand. Had everything one could ask for in those days polyphonic ringtones, speaking alarm clock, music creator. I still remember the days when I used to take my post lunch recess and try to recreate the titanic tune
2007 -

Cleared my entrance exam and got into a medical college. Nokia N series was all the rage back then. I was gifted an N70 music edition by my parents. Came preloaded with some 100 songs or so. I still remember the road trips (was not of legal driving age yet) with one end of the earphones plugged into the N70 and the other plugged into my ear. Surreal experience!
2008 -

The upgrade bug hit me hard and I couldn't resist myself from getting the Nokia N96. Came preloaded with a hundred or so video album songs and the entire Shah Rukh Khan flick 'Om Shanthi Om'. Yup! I watched the entire movie on the phone

Feeling nostalgic about the moments when me and my friends were lying down on the hostel terrace facing the night sky and watching the movie together. Another thing that came included with the phone was a great set of earphones with an integrated remote control. Just had to clip it onto the shirt and never had to remove the phone from my pocket during those long bus/train trips. Unfortunately I got a bit too adventurous with this one. In an age when IP ratings were unheard of, I took the N96 to shoot a motorcycle vlog while on a fairly long trip with my friend. A sudden burst of rainy weather meant the phone was soaking wet and the display damaged. Original display replacement would cost a bomb, so went ahead with a duplicate one and continued using it. Also this was the time when market started shifting towards touchscreens. Having spent 35k on a phone already, couldn't muster up the courage to bring up the topic of touchscreen phone at home. So I went into tinkering mode. Got hold of some website that could make the symbian OS respond to accelerometer inputs. I was determined to make it work and blindly followed the instructions given in the site, uploaded something on to a Russian website, they sent me back a file, downloaded it and installed it onto my N96 and voila! I could control my phone with mere twisting motions of my wrist. Hard to keep that up on a day to day basis though. By the end of almost 3 years, it had become really slow and the battery would just die in a span of 3 hours or so.
2011 -

Time to enter a new galaxy with the Samsung Galaxy S2. Bought one and this was my first foray into touchscreens and android. Loved the android experience which was a breath of fresh air compared to the Symbian. The display was OLED, I had never seen such deep blacks on a phone before. Everything worked flawlessly, but the touchwiz UI slowly weighed the phone down. Formatted the phone a couple of times, continued using it until it was time to let go.
2013 -

I decided to have a clean OS rather than the bloatware rich OS of the other manufacturers. Decided to go with the LG Nexus 5. The phone was smooth as butter. I instantly fell in love with the clean stock android OS. Battery life was the main issue though. By the end of 2014, battery life was becoming a joke. Another issue was the power button loosening up and automatically getting pressed resulting in unintended phone restarts. I still have it with me. Using it as a security camera with Alfred cam app.
2015 -

I loved stock android, but wanted a bit more flexibility. Was wary of bloatware injected UI. Enter the OnePlus 2. The renowned flagship killer was introduced at a killer price. Decided to get one and this was the first time I made a smartphone purchase online. Never visited a mobile shop for purchase since then. Enjoyed the phone a lot. Mine had a sandstone finish at the back which made it very grippy to hold. It is one phone that has aged gracefully. Even after 6 years, it is still snappy. Installed all the updates that OnePlus had thrown in. Currently using it as a secondary phone. I was a OnePlus fan from the moment I bought this phone, so much so that I bought my wife a OnePlus 3 the next year and my cousin a OnePlus 3T the year after that.
2017 -

Oneplus 2 was holding up well, but then I came across this ad of an LG phone being subjected to rugged usage and couldn't keep myself from getting it. Thus the LG G6 was bought. Twin cameras, proper IP 68 rating, military grade 810G durability rating. This was a phone that I would take with me to shoot underwater videos. It was my regular pool companion. And boy did it impress. But the dreaded bloatware issue that I was trying to conveniently forget while getting the G6 slowly cropped up again. Phone was getting slow. Periodic backups, un-necessary apps uninstalled, recurrent formats, nothing worked good. Donated this to my mom. Nowadays, she is subjecting it to proper durability testing in the kitchen, akin to 'Jerry rigs everything'
2019 -

It was decided, I wanted a clean OS with customization options, NO to bloatware, time to rekindle my love for OnePlus. Picked up a OnePlus 7 pro and still using the same. 6.7 in QHD AMOLED with 90 Hz refresh rate is pure awesomeness. The pop up camera ensures that the screen stays clear of any ungainly notches or punch holes. Battery life is great and fast charging is even better. I charge the phone everyday morning when getting ready for work. Everything about the phone feels good and the upgrade bug has not yet hit me, though the phone is nearing 2 years of ownership. I hope to keep it that way.