I'd continue with the main story, as it unlocks a lot of things. At least finish up through 2.0s initial storyline if you have not already (you will know you are done when you get the World's Longest Creditstm).

The MSQ continues at 50 for a while (added in patches 2.1-2.55). These quests reward nice gear and exp, but you can only gain exp past 50 if you have purchased and installed Heavensward. Getting this exp is not necessary to get to 60, but if you plan on playing to 60 I'd go ahead and get Heavensward now as it is a nice boost. You will need to finish all of these quests in order to access any Heavensward content.

I would also rank up in your GC until you reach 2nd Lt, as the housing system is locked behind that rank. Personal apartments are being added this patch, if you want to purchase one you will need to be that rank.

As for whm, if you have not already done so make getting your cross class abilities from ARN and THM a priority. In particular level THM to 26 for swiftcast. At 50+ swiftcast it vital to be able to raise people in combat as waiting out raise's cast time is very risky and might get someone else (or you) killed.

Have fun with whm!