If you’re going to ride it much you should be budgeting for yearly bearing and shock services unless you view it as a disposable bike… Santa Cruz bikes have greaseports that make it simple to keep the bearings well packed with clean grease.
TBH, Heckler or Nuke Mega would be my choices from the above for a mix of UK and Alps.
If SH purchases are now on your radar I’d have a think about whether you’re OK with a well sorted 26er before you do anything else. You can probably pike up a good SH 26er that woud be safe in the Alps from around £500. £1000-£1200 and slightly older 2015 650b Megas with 1×11 drivetrains should be available – possibly even with a set of Pikes if you’re really lucky!