SFI - Tough call - and it's dependent of course upon one's primary investment objective.

Like many stocks they've been bid up pretty good. Would not buy AW.UN or PZA.UN at current price/yield. The one I have added to recently due to yield and stable outlook is SRV.UN. 

BPF.UN and KEG.UN have higher likelihood of dividend increases than SRV.UN and both are fine in my opinion. But currently, as I said and based on my goals I'd go for SRV.UN

FYI a couple or recent additions to my portfolio - primarily yield plays - have been KWH.UN, ED.UN and INO.UN. KWH likely has the best growth outlook (and actually is up about 15% since my purchase which is a nice to have).  
Also, tad more speculative but with possible strong growth potential is PIF (actually just had another dividend increase).
Cheers.