JD 450j or 550J

I am not an operator and need a little guidance picking a dozer for brush clearing and reworking a couple of ponds on my ranch. My plan is to purchase a dozer and sell it in a couple of years. I also plan to operate the unit and occasionally hire some local experienced operator help. I have narrowed the field to either a John Deere 450j, 550j or Cat d4. I will buy a used unit with erops and ripper. Bees are a problem so cab is important. My question, since I do not plan to use the equipment to bill hours for third party work, what is the most cost effective unit. I like the idea of the JD 450j and its favorable pricing over the 550j. There is a 10hp difference and only a few hundred pounds weigh difference so I am thinking thats not worth the money but I don't want to get cheap and regret the decision. The Cat is a little heavier than both but similar HP to JD 550j. I read that the small JD dozers are very good and compete well with similar Cat units. I have cedar and mesquite brush and rocky conditions. I would like to stay with a machine less than 3k hours and 5 to 7 years old and I say that because I think it maybe an indicator for maintenance. I would like the undercarriage to be in good to excellent condition. Your input would be appreciated.