Comparing the Viper PST 2.5-10x44mm SFP scope, which is the older model, to the Burris MTAC. I own the MTAC currently, and also the completely different Viper PST 2.5-10x32mm FFP scope.
The Viper PST 2.5-10x44mm SFP has poor glass quality at 10x, which is where the reticle is calibrated. So poor I found it almost unusable. Based on reviews, this is a design issue, not likely just the example I had. For that reason alone I cannot recommend it to anyone.
The MTAC 3.5-10x scope has, for its price, excellent glass, especially in daytime. It also gets you adjustable parallax through the objective, which works well. For daytime use on a limited budget I think it is a great scope. The knobs are basic, but usable. It is not a fancy or high-end scope, but it has good features for its price point. I have viewed through it from 30 minutes before sunset to almost 30 after and its glass doesn't do well in really dim light, which is typical of most non-premium scopes. I would have the MTAC a half recommendation - it is decent, but not wonderful, and I'm not sure if it's the best value in its price class. For a little more money the SWFA SS 3-9x42mm is a MUCH better scope.
If your budget can accomodate $599 or whatever a used one goes for, look at the SS 3-9x. That will probably also be the most rugged of any scopes in this post.
Another scope you might consider is the Viper PST 2.5-10x32mm FFP scope, a newer PST that has totally different glass. This one actually has really good glass at all magnifications. The exit pupil is smallish at 10x (being 3.2mm) but that's balanced by the scope being relatively small and light. However, this scope has a $799 typical street price, putting it well above the ones you asked about. Although rumor has it Liberty Optics and others may sell them for almost a c-note less than that if you call them up and mention you saw them on the 'Hide.
Yet another scope you might consider is the Weaver Tactical 2-10x36mm, which gets good but not perfect reviews. I don't own and have never seen one in person.
If you need illumination, or just want to go Vortex, the FFP 2.5-10x32mm is a good option. If you don't need illumination or have brand preference, I'd go with the SS.