There are several 4g providers in Jakarta now including XL, IM3, and Telkomsel. I've only had the chance to use XL's 4g and it often tested at 12-15Mbps and as high as 30Mbps if I was in the right area. XL's coverage is pretty good. IM3, if I remember correctly, is much more limited (just around GI and Thamrin). Make sure the network you choose is using a 4g band that is compatible with your phone.
If you have to use 3g though, I'd definitely recommend Telkomsel over the others.
If you have to use 3g though, I'd definitely recommend Telkomsel over the others.