I think that you might be under the effect of a very common misconception.
Whether you choose a 3000 or 4000 Series tractor, they are both the same size essentially.
The 3000 has a 46" wheelbase compared to the 48" wheelbase of the 4000 and the 4000 has four more inches of ground clearance thanks to the larger rear wheels and some changes to the front axle components. So if you are under the impression that a 3000 is significantly smaller than a 4000, then that would be an incorrect assumption.
If you are seeking a tractor that will power a log splitter and a chipper/shredder, then you will need to find one that has a rear PTO valve on it. This is an option on all models so do not expect to find it on every tractor that is for sale. If you decide to go with a 4000, then I think that your long-term interests would be best served with one powered by a Vanguard engine. A 4020 or 4020 PS with power steering would be my choice if it has the Vanguard however I would not turn down an Onan powered unit providing it had been re-powered with a new Onan recently or had been PROPERLY rebuilt by a competent engine shop not too long ago.
The 3012 and 3014 models have Kohler M engines in them and are very capable tractors. Either one will power the attachments you mentioned along with pulling a cart and fertilizer spreader with ease. Your budget will dictate your choice. I doubt that you will find a 4020 with a deck for less than $1500.00 but stranger things have happened. Spending some time in our Classified's forum may help you get a better understanding of tractor values and attachment values but where you live will also affect those.