Either way could work, it really depends on how you are flying the ship. The ship has nice resists so you can put up a decent active tank or a big buffer. If you are flying in a situation where you need to withstand lower DPS for a longer time (eg. vs. cruiser/frig gangs or such especially if they have a tendency to reship) the active tank will be nice. Against high DPS (a BS fleet, for example) you'll probably want the buffer. If there are logistics or RR about go for buffer but focus on resists over raw ehp.

Active tanks tend to use more slots so buffers tend to be used when you absolutely need the extra DPS or whatnot. Armor buffers, however are slower with propulsion mods running and less agile due to the plate mass.

The real acid test for active/buffer tank is to take your active fit, look at how many plates (or extenders, this works for shields too) you can fit and calculate how many rep cycles you need to generate that much raw hp (not ehp). If your fight lasts long enough to rep that much, the active tank has actually given you more ehp than a buffer tank. For example two MARII need seven cycles to beat the 4200 hp from a 1600 RRT plate.