I have got myself a decent collection of lil critters so far, what i would like to know from all you other collectors, which are your personal favourites.

My collection is as follows...Cyclosternum Fasciatum, Grammostola Aureostriata, Grammostola Rosea, Brachypelma Albopilosum, Brachypelma Boehmei, Brachypelma Vagans, Heteroscoda Maculata, Nhandu Chromatus, Psalmopoeus Irminia, Chromatopelma Cyaneopubescens, Lasiodora Difficilis.

So please let throw some names around which haven't been mentioned already

It would depend from person to person what the must have spiders are. I'll bet the majority will say P.metallica and M.balfouri.

For size and impact you could go for Theraposa blondi/apophysis, Acanthoscuria geniculata, a few of the Poecilotheria's, Lasiodora parahybana or many of the Pamphobeteus.
For sheer beauty there are many options but top of the list would have to be Poecilotheria metallica, Monocentropus balfouri, Brachypelma smithi, Grammostola pulchra, Chromatopelma cyaneopubescens and Avicularia versicolour.
For temperament and handling you can't really go wrong with most Avicularia's, Grammostola rosea, Grammostola pulchripes, Chromatopelma cyaneopubescens and various Brachypelma's if you don't mind the flicking too much.

Grammostola pulchra is definately a must have.

I am a complete novice in this regard, but would say that it depends on which specie you like and then see if you then can collect all of the members in that specie
I know that my boet has a love the brachhypelma specie and is collectig all of them

Sounds like a plan to me!

Mexican pink bloom and the avicularia genus. But thats just me!