...or if you prefer, German bocks and Belgian tripels or specialty ales. Those are alternatives, too.
agreed. Basic rules for aging are:
>8 % ABV (ideally >10% abv for extended aging)
dark in color is better in my opinion, of course tripels and belgian golden strong ales are ok too, but you get more complexity from variety of specialty malts in my opinion
Sours can be aged as well of course
heavily hopped or smoked beers (since both hops and smoked malt act as preservative - keep in mind that hop aroma will decay very quickly though).
Beers that don't include volatile flavor/aroma, such as hop aroma, coffee, most spices, fruit (with exception of some sours) etc. - those will tend to dissipate over a period of a few months.
Types of beer appropriate for aging:
Imperial Stouts, BarleyWines, American/Belgian Strong Ales (Quads) - both dark and golden, Belgian Tripels, Eisbocks, DoppleBocks, Baltic Porters, Old Ale, Kellerbier, some examples of Dunklebocks and Weizenbocks, some Scotch Ales, Wheat Wines, Braggots, Lambics/Fruit Lambics, Flanders Red Ale, Oud Bruin, Gueuze, etc.