Torn between Define Mini C Tempered Glass and Meshify C. Yung meshify may option ako na if in case mag ATX ako, ready na. Pero comfortable na kasi ako sa mATX and wala din naman ako balak mag LCS except for the AIOs for CPU only. Plus, pwede ko ipatong yung Define Mini C sa table for display purpose. Hehe.
In terms of size hindi naman sila nagkakalayo, mas matangkad lang yung Meshify C by an inch and a half. Yung desktop footprint nila would be the same :-)
If you are using a Micro-ATX motherboard now I think mas OK yung Define C Mini Tempered Glass in terms of aesthetics. The build will look "full" from the inside and you avoid that blank empty space sa lower portion ng motherboard. Also mas madali itago yung miscellaneous wires connected sa bottom edge ng motherboard for a cleaner look.
For the best airflow I would definitely go with Meshify C. For quiet operation with good airflow I would go with the Define Mini C TG. If dusty yung environment yung Meshify C may need more frequent wiping down kasi dust will definitely accumulate sa front grill. Yung Define C is also a dust vaccum but hindi naman halata from the outside hehe...