SonyEricsson...

• T206 - My first SonyEricsson phone. It was a CDMA phone that ran on the MetroPCS network. It ran fine and was a plain jane phone. It made phone calls. It took phone calls. It had no camera, no color screen, no PIM, nothing. This was just a phone.
• T610 - A great phone. Terrible camera, but great connectivity. The screen was passive matrix, so that was not so hot. The reception of the T610 was a bit shaky. But, the construction and design of the phone was great. The screen was a fingerprint-magnet.
• T68i - I got this one used off of Ebay because it was one that I really wanted when it was released. It is a total geeks phone. One of the first with Bluetooth built in. The screen is terrible when compared to today's standards, but still for a phone released in 2002/2003, it was way ahead of its time. The case for this phone very creaky. This is the only SonyEricsson that I have had which had dedicated dial/hang-up buttons. I loved the two bright blinky lights at the top. Very show-off'y, but very cool nevertheless.
• K510i - This is a great budget phone. It is a lot like an upgraded T610. It comes with a terrible 1.3 megapixel camera which cannot focus on anything past three feet in front of it. Otherwise, it is a fine upgrade from the T610. The reception on the K510i is phenomenal. The screen is the same low resolution as the T610 (128x160), but is active matrix and really bright. It has a nice amount of internal memory (28MB), which is enough to store a lot of (blurry) photos, but not enough for music -- which it has a player for. There is no external memory slot.
• W810i - My current SonyEricsson phone. Very cool phone. Great camera. Great music device. Oh, and it makes clear calls also. Gets great reception. The screen is a lot better than any SonyEricsson I have owned -- it is the first high-res screen SonyEricsson that I have owned (176x220). Like the K510i, the messenging system on the W810i is very efficient and much better than the messenging systems on my RAZR or 6682. This is only my second phone with EDGE (high speed data) support. The other phone is my 6682. Surfing the web with the built-in Netfront browser is bearable when compared with GPRS speeds. What gets a real nice speed boost is the email client. Checking my IMAP4 mail on EDGE is wonderful.  It is nice to have a d-pad instead of a joystick also.