I just checked with Consumer Reports, whose data on reliability/repair history is usually quite good (for US brands, anyway -- I'll see what I can dig up from "Which?" for European models). They say in comparing the two categories of washer, that there is no significant difference as a group in one requiring more frequent repair than the other. Of course, in each category there are going to be brands, and maybe even certain models, that are more problematic than the norm. In the front-load category, CR says this dubious distinction belongs to Maytag. The least problematic was GE's. I should note, though, that the GE, Frigidaire and Whirlpool front-loaders are rated as less repair-prone than the KitchenAid and Amana top-loaders.
Of course, in the DR before one makes a major purchase -- whether car, motorcycle, computer or appliance -- you should always first look into the local availability of parts and service for the models you're interested in. It won't do you much good to buy a top-rated washer in Puerto Plata, if at the first time it needs repairs you have to go to Santo Domingo for parts and there's no local repair guy in the PP area that deals with your brand & model...
The parts question can be particularly vexing in the DR. For example, one of the reasons we brought our Honda with us from the States is that every Dominican told us getting parts for Hondas is "no problem" in Santo Domingo. Well, first time I needed a small repair -- a US$10 part -- I couldn't find it anywhere in SD. Why? Because it turns out that most Hondas sold in the DR are manufactured in Japan, whereas mine was made in North America, and Honda has slightly different parts for the same year and model depending on point of manufacture and assembly! :ermm: