I'm doing 3 day consecutive weeks and it's great.
As for which days, go with what makes sense at your workplace. The only day you're definitely in is Wednesday, so if you have a lot of meetings that are hard to move, or a work culture that means work gets done more early or late in the week, then schedule to be around for those. Meetings can be rescheduled, but it's a pain to fit it in with everybody. If there are pushes to get projects finished that typically happen later in the week, you'll look like you aren't pulling weight if you're not around on Friday to participate. Or like you're going against culture if you're pushing hard early in the week.
If you're lucky enough not to have such worries, it doesn't really matter unless you have a preference. The only possible difference I can think of is if you make a bunch of trips to a bank, as they have lots of Monday holidays, and you won't be able to use your newly found free time to go there on off hours on those holidays.