Its a few years since I've stayed in Ballinamore (last time was 1996 I think) but the most consistent water in the area is certainly Garadice. Connoleys Shore always used to fish well for us and the Church Stretch (also known as the match stretch) is also pretty consistent.
Other lakes we used to do well at are Brackley (north of Ballinamore - head for 'Prospect Point') and Drumcoura, although I think the best pegs at Drumcoura have been ruined by some kind of outdoor centre being built on top of the access.
Its also not far from the River Erne in the north (don't forget to buy a licence for the north though) and consistent areas include the New Bridge (I think its got another name too but thats what all the locals call it), Derryadd Quay and Geeglum Quay.
If you're staying at Ballinamore I would definatly recommend that you stay at the Glenview Guest House (Teresa Kennedy), she's a mine of information on where's fishing (and does a mean breakfast)
I'm sure there's a few other maggotdrowners that have fished around Ballinamore more recently than me but if you wany any more information let me know.