Is this going to be your primary boat?
If so what kinda water are we talking about? Major rivers/resevoirs or smaller (under 5k acres) lakes and rivers/streams?
The 16 Tournament XT will be "marginal/acceptable" with a 25hp. I think you'd be happier with a 40hp on that size rig if you're wanting to fish tournaments and/or tournaments on big lakes. The 175 XT I'd want at least a minimum of 50hp with preferably a 60-75hp were it my primary boat. The 25s were value leaders sold strictly for price. You'll be doing good to break 25mph with a fully loaded 16 with only a 25 pushing it.
I'm currently looking for an aluminum rig myself and obviously Bass Trackers are available 10-1 over anything else because they have been the best sellers for the last 3 decades. (It was Johnny Morris who pioneered the package deals on a national level and it began with the BTs back in the late 70s.) But I'm buying this strictly as a secondary/small water rig to carry my boys in. The 16 is what I'm most interested in and if I get a 16XT I'll refuse any smaller than a 35-40hp.
I see smaller aluminum rigs (14-17ft) on KY Lake/Pickwick all the time but that doesn't mean they are enjoying the ride when the wind kicks up or the traffic is heavy. But realistically those guys aren't running the lakes end to end, they put in a specific ramp and typically stay within 10-15 miles tops of the ramp. We're talking about 25-30mph boats so running much further wastes alot of time and you probably could've been time and money ahead to put in at another ramp in such situations.
Quality wise, well they are built for MASS PRODUCTION and they spit them out as fast as they can. So obviously there are better aluminum rigs out there. But like ANY boat, buying used mainly means the condition and maintenance with which the boat was kept up with by previous owners. Pay attention to rivets (they'll leak as they age) and thoroughly check the decks and floors for rot. The older ones are notorious for leaking rivets which then waterlogged the foam under the flooring and decks which makes them MUCH heavier over time.
You can buy fully welded, all aluminum boats but you'll certainly pay more for them.