If you ask 10 people which servo to get you'll get 10 answers, people are just going to recommend what they run and won't necessarily have tried every alternative (either at all, or long enough to see wear and premature failure issues). Savox have high current draw so they can cause issues with some ESC BECs, but in nitro if running a dedicated 7.4V pack it's probably not an issue. With that said, more efficient servo = less recharging too, so it's probably safe to skip them if you're already so-inclined.

Using the same servos is usually so people can carry a single spare, most good servos these days are pretty durable though so I think it's fine to choose different ones. Given a budget restriction I'd be inclined to bias that budget towards the steering servo a little.

Just keep in mind that claimed specs are just that - arbitrary manufacturer claims, and brands like Protek / Tekin / others sometimes use "dynamic torque" ratings which are inflated and not actually comparable to traditional stall torque measurements. The servo market has exploded in the last decade and unfortunately there are little to no objective 3rd party measurements of claims. This means that when someone says "get a minimum of xx kg for steering" - it depends what their brand/s of reference for that value is.

I'm personally a fan of Futaba and Sanwa servos, definitely more expensive for the good ones, but genuine and honest claimed ratings + very long term reliability / durability / efficiency.
You'll get a million other recommendations though so button up for doing a bit more research. Longevity is an important factor when dropping even $90 on something, IMO.