I suppose the question isn't very specific...
A. Simply, but permanently butterflying the Moorish Conquest.
See above : you have a whole net of non-conflicting possibilities to make the Arabo-Berber conquest butterflied or failing.
B. Making Visigothic Spain more of a regional power (maybe with a fairly early PoD regarding Spain's conquest by the Visigoths and the earliest days of the kingdom?).
Well, it *was* a regional power in its time. It did suffered from some issues.
The first of which was homeism, and hostility towards orthodoxy during Euric's reign. It can be butterflied, but I'd expect Visigoths to take less of Gaul and Spain as it was associated with an expansionist and anti-Roman (in the geopolitical sense) policy, and making them less of the huge player they were.
Eventually, Alaric II tried to smoothen things and to pull a Theodoric regarding religous differences (aka, tolerating orthodox, homeans and others), but it failed (and I don't think it would giving the multiple hostilities).
It's possible that the Battle of Vouillé could turn differently, though, as with Alaric living on (and stabilizing the Balthi succession with possibly keeping more of Gaul than IOTL) and/or defeating Clovis.
At this point, though, Franks became a power to be reckon with and even without Clovis you'd probably see the maintain of a Frankish-Burgundian alliance (at least until one of the Franks simply conquers Burdungy, that is).
It would still allow Visigoths to look a bit more as Ostrogoths when it come to rule, but I don't think it would really butterfly away religious issues (that would certainly allow for more Frankish intervention), revolts (as Peter in Ebre's region) and particularism (with a likely establishment of sub-kingdoms), meaning the same problems than IOTL, maybe atoned.
I suppose you could easily make Goths orthodox from the beggining, having Valentians having a nicean religious policy instead of homean, and therefore augmenting chances having nicean missionaries converting Goths.
It would certainly, however, change many things regarding Gothic history in the IVth and Vth history without certainty to see them settling in Aquitaine to begin with and then in Spain.
C. Making a more centralized kingdom, a la France, out of the Visigothic Kingdom using PoD.
I suppose you mean either "classical" Merovingian Francia or later Carolingian Francia, rather than contemporary late Merovingian?
You'd definitly need a dynastical stability. Ostrogoths fucked it up during their rule in Spain, so you'd have to boost one of the short dynasties : I'd think making Liuva/Liuvigild/Reccared/Liuva II dynasty living on being the best chance.
At this point, councils weren't yet the tentative of stabilisating institution it became, and you had a chance to establish a dynastic succession rather than legitimisation of coup and its transmission. Not that of a big chance, though : two centuries of political troubles let traces, and nobody was that interested on a strong kingship safe orthodox clergy (and that blostered anti-clerical and anti-royal revolts à la Witteric).
I suppose Liuva II managing to defeat Witteric would help, but that would be but one of the obstacles for a young king, and it would be a given to have more revolts for various reasons. It could be defeated, and really helps having a stronger kingdom, but it wouldn't be that easy.