What is the best lexus or reliable sports car I can get for around 20k? Want it to be somewhat reliable.?

If you mean a two seater convertible , probably a Mazda MX5.  (Miata), if possibly an 8-10 year old Porsche Boxster,but if you include sports saloons there’s far more choice.

Subaru WRX is reliable and much much quicker than an MX5 and had  AWD for bad weather. 

Ford Focus ST is a pretty good choice too and generally cheaper than its main rival the Golf GTi .

Another good choice would be a BMW 335d, which is sub 5seconds 0-60 and has diesel economy as well as AWD.

My brother has a Lexus RX and he seems really happy about it. Meaning the RX is a fantastic eco-friendly family SUV that’s is also available as a seven-seat RX L Hybrid. No plugin in required. RX has a 3.0l petrol engine with automatic (E-CVT) transmission. Lexus Self-Charging Hybrid cars have a petrol engine and an electric motor.

I don't have a Lexus but I do have 2 Rolls-Royce cars. I suggest Rolls-Royce, It's luxury made and is better than Lexus. I have a Rolls-Royce Phantom VII & Rolls-Royce Ghost. The best Rolls-Royce is Rolls-Royce Phantom VII. I don't know monthly payments (I paid RRP) but here is the link....https://www.rolls-royce.com/

Don't even bother with a Lexus! They are just over priced Toyota's. They will be no more reliable then the Toyota counter part and if you want performance just more money with no more fun.

At the core of this issue is what makes a car a sports car. If it is handling and being able to get down a winding road fast, very few cars (for the price) can beat a Miata. The only car I have driven that can was a RX7. But the RX models have been discontinued and a rotary engine is very temperamental. Operated wrong they fail on a regular basis. Operated right they last till the driver forgets two or more times (some times once).

If a sports car to you is something that is fast on the freeways- then get a Mustang. It like the Miata would have to be used to be in your price range.

Some see the Corvette as a sports car, but they have along wheel base and are not cheap even used(unless it has been trashed).

For what it is worth my NA Miata is still on the road and runs like a champ. They might not have all the torque of some other sports cars, but the cars that have more torque often do not have as good a driver (at least when I am behind the wheel).

See if you can find a Subaru BRZ or Toyota 86 if a Miata is too common for you.

Only get the Miata if it's a K24 swap.

I wouldn't waste my money on a car that will only last about 200K.

I know my 2004 CR-V EX has had no major issue since I bought it in 2004. It has 240K miles, starts right up every time, doesn't blow oil or any other fluid, drives nice, has 4wd and I wouldn't be surprised if went beyond 300K miles and another 5 years.

I'll never buy any but Honda 

Look for a good used Mazda MX-5 (Miata). They are fun to drive, especially if you get a manual one, and they have a proven track record for reliability. 

Shop around. This is a dumb question to ask really. Go buy a Ford Fiesta.