Unfortunately, every brand handles the divisions differently within its own product line(s) and every optic has its own advantages and tradeoffs within a given price range. There's not really a way to know if an optic is "good-to-go" without evidence or testing it out yourself. Specs can be misleading since they may or may not be accurate, and optics (even LPVOs) have internal components that need to be designed, sourced, produced, fit together and QC checked. The spec sheet won't tell you that "Brand X" saves $10 per optic over "Brand Y" by using a lower-grade epoxy that may be less resistant to vibration or temperature cycling.
Fortunately, there are lots of optics from reputable brands that have considerable run time and whose pros/cons are well described. The Vortex Razor LPVOs are an excellent example. With some searching you will probably find that the optic has good glass and is durable with an easy-to-use reticle with a tradeoff on weight within its price range.
What is your definition of "serious use", and what characteristics do you value most in your setup? My general recommendations when it comes to LPVOs are:
1. Define what you realistically intend to use the optic for. If you plan to shoot off a bench once a month at 25yd with no pressure, a Strike Eagle may be fantastic. If you plan to be jumping out of vehicles and need to identify threats at distance, the Razor (or equivalent) may be a better choice. Use and reticle choice matter as well.
2. Stick to trusted brands that have run time on their product. They will probably have more reliable warranty support as well should something be off with your optic. They are also less likely to disappear leaving you SOL in 2 years when something breaks. If it's an optic you plan to depend on, why be a guinea pig? Chances are good you will save money, time and frustration by sticking to the brands that have been around.
3. You get what you pay for. Quality materials, fabrication, assembly and quality checks cost more. If two optics have similar specs but one costs significantly less, that difference is probably accounted for in materials and quality checks.
4. There are always trade offs. For example, the Nightforce NX8 is super small and lightweight, but the eye box is very tight and the reticle is not well suited to precision. It is a close quarters focused optic which happens to have 8x high end magnification. Refer to #1.
5. If you are on the fence between two "levels" of a brand offering, it's almost always worth saving a little longer to pick up the higher end optic.
6. Lastly, don't skimp on the mount and account for this in your budget. A cheap, crummy mount holding a quality optic is like putting corner store used tires on your race car - all the horsepower in the world doesn't matter if you can't put it on the road.