England start
Here's my England, 1427, Protestant (come the reformation) WC attempt.
I've completed the Occupy Paris mission & retaken all the cores granted, & seized Granada & Gibraltar by annexing Granada. I've also just converted to an Empire (had a lucky adviser event giving 2 stability & took advantage of that), & taken Vlaanderen. Infamy is at just under 4 points. Stab 3, WE about 7. Legitimacy is down to 60 odd due to the change to Empire.
Scotland was annexed in 1413, so there's another 26 years to wait before I get the necessary cores to form GB.
I've only vassalised a couple of Irish states due to missions, I'm waiting for the cores from forming GB to avoid the Infamy. I've also vassalised Navarra (to allow land access to Castille) & Aquileia (as it's in the not so soft belly of Austria).
I've PU'd Castille, Denmark, Hungary, Lithuania, Muscovy, Poland & Sweden - Henry IV is still King. Re the PUs, I was extremley lucky to get that event that offers 3 free spies, otherwise I wouldn't have PU'd so much. On the other hand, it did take 3 spies to Fab Claims on Sweden, one even failed at 88%.
As far as cutting out the colonial competition goes, I've clobbered Portugal a couple of times, but their legitimacy has just been resurrected by a new ruler, there's a revolt ongoing in Portugal at the moment that I'm cheering for, & their navy's down to only 5 carracks. Castille is PU'd, which usually stops them colonising more than the odd region.
Having so many PUs in the east makes it pretty likely I'll get a nice land border with the hordes to allow me to colonise through them.
Austria, HRE leader & with an 84k army to my 50k is the only threat at the moment, it is pretty much surrounded though, plus, I've no need to tackle it at the moment.
Plan from here is to Holy War, gold provinces of Morocco first, then Jerusalem with the aim of pushing down into the gulf, heading for Mecca. I'm fairly comfortably Papal Controller, so can get a crusade bonus in, probably against the Mamluks, who hold Jerusalem & a lot of the rest of that region.