We have had the Grizzly G0555X for almost a couple years now and it has been good to us. Had to re-tap a couple holes in the castings on assembly when it was new, but the saw has served its purpose since without any real issues. I’ve looked at the harbor freight in the store and it looks fine for the price, though the blade adjustments may be a little annoying. You may also want to check out the Porter Cable at Lowe’s if they still carry it. For years the Delta 14" was the standard in this class of saw, but it’s since been discontinued. I have one and while the adjustments are nice, the 3/4 horse motor is kind of weak.
The real differences between these saws is in the blade guide adjustment, and some of them may have a step pulley for different speeds. However, for aluminum, you want a fast blade speed, not slow.
I have a Delta at home, and the team has one as well. Both have the “metal cutting” reduction gearbox, as well as the usual stepped pulleys for finer-grained adjustment. Aluminum isn’t terribly picky and a fairly wide range of speeds will work.
When I cut aluminum at home I generally run it at a faster speed because, well, it cuts faster that way. The team’s saw stays on the gear-reduced slower speed because it’s used by students of varying skill levels. It’s quieter (you can explain while doing) and less intimidating. It’s also somewhat safer, since a low speed blade break is less of an event. It’s still reasonably fast on all but very thick (1/4"+) aluminum.
In general, I lean to toward teaching work methods that stress care over speed. It’s faster that way
If you go to Home Depot’s site and compare, you can see the price performance changes from HD’s Ryobi at $130 with a 9" throat and a 2.5 amp motor.
Then jump up to the WEN at $230 with a 10" (9.75") throat and a 3.5 amp motor.
Versus making a bigger jump to $400 saws with a 14" throat and a 9 amp motor.
We have made due with the Ryobi for 6yrs, but would like to upgrade to a more substantial machine. The larger throat would also allows us to make more cuts with a band saw as apposed to requiring a pre-cut with a jig saw before cutting material on the band saw.