Honestly, I think the reason that I am inclined to pick the older titles is because of the good memories that I had. Halo CE: Really the start of something brand new for consoles. I can remember just entering high school when one of my friends bought and xbox and halo. I remember thinking what in the world is an xbox. Before you knew it we all had them, and we had 16 guys in my basement every weekend playing. The fond memories of 8 tv's and 8 xboxs, and friends yelling back in forth at each other really gets me. Halo 2: Prob my favorite of all the games. Just because that was when XBL was first introduced, and really my first opportunity to meet/play with a wide range of people. Granted it had a host of problems. Lags switches, glitches, button combos, which all hurt the gameplay. But nothing can replace the many fond memories I have from that game. Also the maps were awsome in halo 2. Halo 3: Halo 3 came out while I was in college so I was not able to play this as much. Although there were some problems, I feel like it was the most competitve halo. The ranking systems worked for the most part, and once you reached level 47 you started to play a lot of good players. Overall, the maps were ok...not the worest of the bunch but not the best. Reach: This was a huge disappointment to me. I played the beta and was so excited, but when the game came out I was very dissapointed. For me the AA's runied the game, and the bloom has a host of problems. Not to mention the maps for a huge oversight on bungies part. Maps are the backbone of MM, and they are lacking in that department. Forge is awesome, could always be better, but it is so much better than 3. Yet, my biggest problem with reach would be the ranking system. I feel like I can't play competitively anymore. I might get 1 in 10 games where I play anyone that is ok, and the other 9 would be me going 20 and 4. Therefore, IMO this is not an enjoyable experience for either party. It is not enjoyable for me because it is not challenging, and it is not enjoyable for them because they are being destroyed. That is just my opinion though, and there are many counter arguments to it. I will not bash bungie though, they have done their best to cater to everyone.
Old games have all the originals that peiple love. Games go on and on and people start missing the first.
The biggest thing I miss from Halo:CE was LAN parties. Little kids screaming in your ears on Halo:Reach is nowhere as fun as seeing your friend jump out of his chair and cuss at you as you melee him into the ground. I played Halo 2 in LAN parties, too. Gaming community has been flooded with kids taught nothing from their parents. It's like they get no attention at home and just let loose on Xbox LIVE. I used to love the team aspect of using headphones, but it has lost all of it's appeal nowadays.
If you have problems getting games that are too easy, do what I did and start playing MLG. I hated it at first, but once you get into it, it's serious fun, and I rarely get matched up with people who completely suck. Which means it's competitive, tough and fun. Halo 2 was great and so was CE (Granted the majority of my CE time was on PC), Halo 3 was my favourite for custom games. Reach was my favourite for Matchmaking.
The older halo games are classics and can never be replaced =) Halo: Combat Evolved= First major change in gaming Halo 2: Major change design Halo 3: Goin out with a bang!