The 31-year-old striker spent the second half of last season at Fir Park and helped Well avoid relegation.
"It is quite easy for me to make that choice, but I have got other options further afield - abroad," he said.
"I did state I want to get back down to England again - I do feel there's some unfinished business there."
McDonald revealed there had been talks with clubs in England as well as Motherwell but suggested it was "early days" as many managers and chief executives had only just returned from summer holidays.
"Obviously it's nice to have a few offers, because we know that in football at the moment it's difficult times for a lot of players," he told BBC Scotland.
"It will be decided with me and the family. My wife's pregnant again, a big bearing on everything, so it's taking a bit more time than usual to get it over the line on what we want next."
McDonald, who won 26 caps for Australia, spent three years with Motherwell and had a similar spell at Celtic before time in England with Middlesbrough and Millwall.
He returned to Fir Park after being released by the Lions and scored five times in 13 appearances before Motherwell beat Rangers in the play-off final.
"Motherwell have been very good to me over the time I was there - this time and the time before," said McDonald, who added that the club had a strong place in his heart.
"We've always loved living in Scotland, me and my family, and I still have my house up there as well."
John Sutton has left Well for St Johnstone and Lee Erwin has joined Leeds United this summer, with manager Ian Baraclough already recruiting David Clarkson after his exit from Dundee and fellow striker Wes Fletcher after his release by York City.
McDonald was full of praise for the man who took over from Stuart McCall midway through the season.
"It was obviously difficult circumstances, but thankfully we got through it in the end and it was a fantastic ending to what was probably a disappointing season all round for the club," he said.
"I fully believe that, with the manager in place, and the assistant that's there now, the club's in great hands and I think it's on the up again."

However, the discourse has mostly centred around the "maharajas" or kings, many of whom are still wealthy and influential.
Although there have been prominent maharanis (queens) like Gayatri Devi of Jaipur, who was instrumental in promoting girls' education in India, and featured on a Vogue list of "most beautiful women", many of India's royal women have been out of the spotlight and not much is known about them.
A photography studio, Tasveer, is now trying to change that - as part of its 10th anniversary celebrations, it has collected portraits of Indian queens and princesses and is showing it in an exhibition, titled "Maharani: Women of Royal India".
Tasveer said the pictures were sourced from the archives of the Museum of Art and Photography, royal collections from across the subcontinent and other institutional and private collections both in India and abroad such as the Victoria and Albert Museum, the National Portrait Gallery in London, and the Amar Mahal Museum and Library in Jammu.
Scott McDonald suggests there is "a huge chance" he could return for a third spell with Motherwell but says there is interest from other clubs.
[NEXT_CONCEPT]
India's royalty lost their official powers when the nation gained independence in 1947, but there is still a great sense of romance and fascination with the men and women who once ruled large tracts of the country.