Probablty a 5 star,,, i found this site to have the best hotel prices of any I have looked at.

http://chinatour.net/shenzhen-hotels.html

I like Greentree Inn. Cheap, usually clean and in every big city.

hanting near the train station but use elong.net

Jinjiang Inns are great value. I have stayed in a number of then and always found them to be in decent locations, clean and very reasonably priced.

7 days inn is cheap and reasonable.  about 200 rmb per night

  Best hotel chain? The one on the toilet I was using when I had food poisoning in Guilin. I must have used that thing about 300 times. It never broke. Real quality. So much poop and vomit though. So much poop and vomit. 

I like the Home Inn chain. They are consistently clean and well kept in the ones Ive stayed in all over China, inluding Shenzhen.

My friend stayed at the Vienna hotel near the Dongmen shopping area before. It is clean and well maintained and near to Guamao station also and the HK border

Reasonably priced around 200 RMB

jinjiang inn. looks like a western hotel

I like the green tree in , you can find them in southern china, very clean, and the staff is friendly.

What do you mean "most reliable"? Like it'll be there when you arrive?

Yeah obviously a 5 star hotel would be ideal and "reliable", but if you're just looking for a relatively cheap night still good enough to leave you bags and go out Home Inn and 7 days are usually OK.