I too will need a new apartment in November, though I am nowhere near the type of high-end property you're discussing. So far I have lived in Palermo Soho, Las Cañitas, and microcentro. I liked Palermo the best, microcentro the least. Cañas was nice, but loud and expensive, although proximity to the park for walks was great. What I'd really like is to find a place a bit north, Villa Urquiza, Villa Ortuzar, Agronomia (good luck!), or somewhere near there. Villa Pueyreddon would be OK, but there's no Subte. Nuñes is nice, but a bit too pricey for me.
Real estate agents here are scum, and I despise them with a passion. I had that experience of getting jacked up for another commission when renewing the lease, and then the woman was snotty and condescending to me on top of it.