10-15K Suggest a 5G enabled previous year's Flagship phone.

But still receiving security updates
Yes and still 100% usable. Android 13 just feels old on paper.

I upgraded from S20FE 5G to S23 & the most noticeable upgrades to me are the smaller size & better selfie cam, that's it. Software has changed but won't consider it significantly better. I upgraded my phone because my father wanted a new Samsung phone & S20FE5G is still better than any Samsung phone below S23 in my opinion. Also, a better battery life.
 
Yes and still 100% usable. Android 13 just feels old on paper.

I upgraded from S20FE 5G to S23 & the most noticeable upgrades to me are the smaller size & better selfie cam, that's it. Software has changed but won't consider it significantly better. I upgraded my phone because my father wanted a new Samsung phone & S20FE5G is still better than any Samsung phone below S23 in my opinion. Also, a better battery life.
I have both phones. The S23 is the one with the sim and the S20FE is the media consumption phone and backup phone.

I didn't want to trade it in for the S23
 
You wont get flagship for 15k, if you want true flagship increase your budget and get S23. Used one will cost less. or else check the FE modesl
FYI - There were 4 FE models sold in recent times, 3 of them are bad, namely S20FE 4G, S21FE & S23FE (mainly because of battery life). S24FE isn't as bad as S23FE, even GSMArena review can attest to that but still not a great choice.
 
FYI - There were 4 FE models sold in recent times, 3 of them are bad, namely S20FE 4G, S21FE & S23FE (mainly because of battery life). S24FE isn't as bad as S23FE, even GSMArena review can attest to that but still not a great choice.
My wife has S20FE 5g, still no complaints, but there won't be any further updates, so won't recommend it. Look into motorola, they have quite good phones in recent years.
 
My wife has S20FE 5g, still no complaints, but there won't be any further updates, so won't recommend it. Look into motorola, they have quite good phones in recent years.
It is great hardware wise, especially the camera. Android updates don't add much these days anyways, so in a way can consider.

My first recommendation is usually a new phone for sure.
 
I am not looking for a new smartphone; I am interested in a used one. I am fine with flagship models from before 2023.
S20 FE 5G is still a great phone. I got it 2 years back. Still going strong (battery life is a bit weak, getting around 4.5 hrs SoT with 85% limit charging).

If you want to go for new, iQoo Z9 is a good device. i got it for my mom. It is quite smooth.

Also beware of installing new OS updates in old phones. Many phones are having green line issue after installing updates (especially in Samsung and OnePlus phones). If you buy a new phone atleast you are covered with display change due to green line issue.
 
Also beware of installing new OS updates in old phones. Many phones are having green line issue after installing updates (especially in Samsung and OnePlus phones). If you buy a new phone atleast you are covered with display change due to green line issue.
I've updated my S20 to the latest with no problems. And it was 12 to 13 followed by all security updates as I'd not updated anything since I got it.