If you're talking about buying new, someone might be able to make a comparison. If used, the Bounty Hunter Time Ranger has been improved 3 times, so there could be quite a variation.
The Fisher F4 I have, ground balance only works in all metal & think the older Time Ranger I had was the same way. My ground is highly variable & it is hard to detect anything beyond 4-5" & to get an accurate ID beyond 3"-4". My deepest coins ever about 7" & this is only possible in about 1% of the ground I detect.
The Garrett Ace 250 isn't a bad detector for just over $200 new/$150 used. It will ID coins down to 4" here, 6"+ in some soils. For over $500 new there are better choices, but that may be about as good as any under $500.
The Fisher F4, while I'm selling mine to get a more expensive detector, is OK for the price. The optional 10" coil is under $60 & will cover somewhat more area & maybe go a bit deeper.
Maybe others can add to this. Good luck & happy hunting, George (MN)