Make sure you do a clean install when trying new navcores. Do not just overwrite files when changing navcores.
First try navcores 9.430 and 9.465 from the following threads:
Navcore 9.430 Patched for Start
Navcore 9465 for GO X20, X30, X40, X50, One IQ Routes, XL IQ Routes, XL Live, Xl IQ R
For the 9.465 navcore, make sure you download the LE cab, not the GO cab, for your Start XL device.
Unfortunately it is difficult to recommend a navcore that you would like, as not all models are the same and everyone's tastes are different. The only way is to try a few (or many) navcores... it's all trial and error.
All the best!