My slightly biased opinion
I would go with a Stihl ms230 if you don't want an upgrade. Don't go with the quick tensioner model, I find those to be a pain. From what I can find, your current saw is 42 cc, the Stihl ms230 is just over 45cc. They are pretty equal.
However, you haven't specified how large the logs are that you are cutting, so a Stihl ms170 or Stihl ms180 (30/32 cc respectively) may also be enough for your needs.
The Stihl ms230 can run bars from 16 to 18 inches, I've never used a Stihl ms230 so I can't say how it handles those bars.
I personally wouldn't buy new, I'd find something from facebook that has been serviced recently, or it's in newish condition. Whilst this may cost you a couple hundred (I'd say MAX 250-300usd), it's a saw that will last you a lifetime with the proper maintenance. I've owned a Stihl ms170, a Stihl ms261c-m and they never let me down, always started second or third pull and preformed well. I've got a larger Stihl ms461 arriving tomorrow that I purchased from a member on this forum.
That's my 2 cents.