Hi Paul!
I must say, my motivation has changed drastically over the years.
Initially, it was just an "O, How pretty" knee jerk response which is an honest and sincere emotion but not necessarily the most wise.
Certainly though, this is the deep seated root of the love that grows to support one's ongoing "interest" in orchids; so by no means am I intending to diminish it.
At some point however, two things occur:
1. We run out of space
2. We kill things...(but not so quickly that we outpace the acquisition of more plants)
This inevitably leads to the pursuit of knowledge. I have purchased many volumes of books and looked for information on line. Cultivation, disease control, lighting requirements.
...and OMG different genre of orchids require different growing conditions???
ETC.
Now I have enough time and information under my belt to know what I think is the "prettiest" for my limited space and time:
I enjoy BIG BIG flowers! However, I am willing to have small flowers if they are unique.
I am willing to wait for flowers if they are spectacular...thus I don't mind plants that bloom only once per year for a few weeks.
I love learning about orchid history and vintage plants.
I am best at intermediate to warm growing conditions.
Conclusion: I currently prefer large flowering cattleya species and hybrids.
I try to collect unique and historic plants.
When I go orchid shopping now, my purchases are directed to buying less plants with each plant costing more than I used to spend.
I have not eliminated other species of orchids entirely and have a few dozen favorites like Dendrobium cuthbertsonii that has more of a cool cultivation requirement but I seem to keep very well.
If there are any recommendations I could make for anyone starting with orchids, it would be to try new things, keep an open mind, get educated, and have fun!