Here are the factors that you need to consider when making your choice, both objective and subjective:
1) Sound preference and noise level
2) Material / durability
3) Ease of instillation / fit
4) Comparability with future mods
5) Cost
The first one is very subjective. YouTube and car events can help you determine what you like. Some guys like the deep sound of straight through mufflers or glasspacks, some like the tinny sound of chambered mufflers. Some people like drone, some don't. Some of us need to be able to start their cars in the morning without waking up their sleeping kids and the rest of the neighborhood, some want to wake up everyone in a 1/2 mile radius. I think some people here can give you objective input on the noise level aspect, especially if you still want to hear your radio when it's done. Also, keep in mind that engines get a lot louder as they start moving more air. If you plan to add heads/cam later, a borderline noise level system with a stock engine may be intolerable with a built motor. You stated that you're running cats, and they can reduce the noise level significantly, so if yo uwant "loud" you will have to pair up a louder system.
#2 and #5 play together. I like stainless because of the durability factor. I want to buy something once and never worry about it again. If this is a daily driver in a snow belt state, you might consider stainless (+$$$) as a critical factor over an aluminized system. It all depends on the use case and if you have to deal with salted roads in winter seasons.
Number three can be important depending on your budget and tools available. You don't want to shell out your bucks on a "bolt-on" system and have to drop an extra $100+ for a shop to make it fit. Read lots of reviews or get input from people who have the system you're considering before you buy. (I'll never forget the JC Whitney exhaust system my buddy in college bought for his '69 fastback - NOT EVEN CLOSE.) Lots of people here can provide feedback on this point. Talk to the distributors like LMR for recommendations on cat-backs or if you're piecing mufflers, tails, and flow tubes together. They don't want you to return their parts, so it's in their best interest to provide a good recommendation based on your build and their general customer feedback.
Not all systems are routed the same. Some follow the factory path, some use slightly different routing for larger diameter pipe / smoother bends. For example, If you plan on installing an MM panhard bar later,
Flowmaster is the only aftermarket brand they state will fit without modifications to the tailpipes. Not a huge point but something to consider.
Number 5 rules them all. However, a cheap system can become an low-quality expensive system if you have to modify it or end up taking it to a shop to make it work.